Analysis of application in reducing cow's milk protein allergy

Cow's milk protein allergy is an abnormal immune response caused by cow's milk protein, which is common in infants and young children. It is divided into IgE-mediated and non-IgE-mediated. When allergic people consume foods containing cow's milk protein, IgE will bind to it, activate mast cells and eosinophils, and thus trigger an allergic reaction. These cells release a large amount of chemicals such as histamine, leading to symptoms such as vasodilation, skin itching, and respiratory symptoms. There are also reports of anaphylactic shock caused by consuming cow's milk protein. Due to the immature digestive tract barrier function, loose intestinal wall structure, high mucosal permeability, and limited ability of the acquired immune system of the small intestine to process antigens, excessive exposure to antigens or inappropriate antigens destroys the self-stability of the intestinal mucosa. In addition, the normal intestinal flora of infants has not yet been established, which makes it easy for the gastrointestinal mucosa to form an immune inflammatory response, and corresponding gastrointestinal symptoms such as vomiting, diarrhea, abdominal distension, intestinal colic, and gastrointestinal bleeding occur. Therefore, it is necessary to study the mechanism of cow's milk protein allergy in order to develop desensitizing and hypoallergenic infant foods.

Research results sharing

β-lactoglobulin hydrolysates of Lactobacillus plantarum AHQ-14 and Lactococcus bulgaricus BD0390 can reduce the allergic reaction to β-lactoglobulin in sensitized mice

Abstract

β-lactoglobulin (β-Lg) in bovine whey protein is highly allergenic. β-Lg allergy often leads to gastrointestinal allergy or allergic gastroenteritis, destroys the balance of intestinal microecology, and seriously affects infant growth and health. Milk protein can be partially degraded by lactic acid bacteria (LAB), which can reduce its allergenicity to a certain extent. The immunological model of β-Lg hydrolyzed by AHQ-14 (H14) or BD0390 (H390) was studied in a sensitized mouse model. BALB/c mice were sensitized with β-Lg or β-Lg hydrolysate, and then sensitized with high doses of β-Lg or β-Lg hydrolysate orally. The total IgE and IgG levels of mice stimulated with β-Lg were increased. In contrast, mice stimulated with H14 or H390 suppressed allergic symptoms and reduced serum IgE/IgG levels. The H14 and H390 groups also reduced the concentrations of mast cell protease 1 (mMCP-1) and plasma histamine (HIS), inducing T helper (Th) 1 cells or T regulatory cells to regulate Th1/Th2 immune balance. Mice stimulated with H14 or H390 showed no signs of intestinal inflammation, maintained normal IL-4 and IL-10 cytokine levels, and increased IFN-γ production. Therefore, H14 and H390 can protect and avoid clinical allergic symptoms in mice and have the potential to be used for β-Lg allergy, providing a safe and effective treatment for infants with cow's milk allergy.

Conclusion

In this study, β-Lg hydrolysates of Lactobacillus plantarum AHQ-14 and Lactococcus bulgaricus BD0390 reduced the clinical response of β-Lg-allergic mice and prevented the occurrence of intestinal inflammation in β-Lg-stimulated mice. In addition, the regulatory mechanism mediated by hydrolysis of β-Lg was triggered. The levels of IgA, IL-4, and IL-10 in the H14 and H390 groups were similar to those in the control group. Therefore, the detected H14 and H390 not only avoided the indications of inflammation, but also changed the typical immunological characteristics of food allergy pathology. H14 and H390 have safe application value and therapeutic potential for animals and infants allergic to β-Lg.

The degree of hydrolysis does not well predict the allergenicity of milk whey and casein hydrolysates in the rat milk allergy model

Abstract

The use of infant formulas (IFs) based on hydrolyzed milk proteins to prevent milk allergy (CMA) is controversial. The risk of interferon-induced milk protein sensitization may be affected by the degree of hydrolysis (DH) in interferon and other physicochemical properties of cow milk protein hydrolysates. The immunogenicity (IgG1) and allergenicity (IgE) of 30 whey or casein hydrolysates with different physicochemical properties were compared using the rat CMA peritoneal model.

Conclusion

Whey-based hydrolysates showed higher immunogenicity than casein hydrolysates, inducing higher levels of hydrolysate-specific and intact specific IgG1. The immunogenicity of the hydrolysates was affected by DH, peptide size distribution, peptide aggregation, nanoparticle formation, and surface hydrophobicity. However, only surface hydrophobicity was found to affect the allergenicity of the hydrolysates, as high hydrophobicity was associated with higher levels of specific IgE. Whey protein- and casein-based hydrolysates showed different immunogenic properties, with highly diverse molecular compositions and physicochemical properties that could not be explained by measuring DH, which is a poor predictor of allergenicity. Therefore, future studies should consider and take into account physicochemical properties when evaluating the allergenicity of milk protein hydrolysates.

Discussion

IFs based on hydrolyzed milk whey or casein are commonly used in the treatment of CMA. Allergy involves complex immunological mechanisms, and the allergenicity and immunogenicity of 30 different whey or casein hydrolysates were compared by specific IgE and IgG1, respectively, and the molecular and physicochemical properties of the hydrolysates were comprehensively characterized. Results: Hydrolysis was found to reduce the allergenicity of whey and casein proteins, likely due to the hydrolysis of allergenic epitopes within the proteins. The commonly used hydrolysate parameter DH was not found to affect allergenicity, measured as the ability to induce intact milk protein-specific IgE. Instead, DH affected the immunogenicity of the hydrolysates, with increases in DH resulting in decreased levels of intact milk protein-specific and hydrolysate-specific IgG1. Whey protein hydrolysates retained higher levels of intact milk protein-specific and hydrolysate-specific IgG compared to casein hydrolysates, suggesting that there are intrinsic differences in the immunogenicity of whey and casein hydrolysates. This difference cannot be explained by DH, as casein-based hydrolysates have lower DH overall than whey-based hydrolysates and should therefore theoretically retain more intact milk protein structure. It was confirmed that hydrolysis of whey and casein proteins resulted in the formation of hydrolysates with highly different molecular compositions and physicochemical properties that could not be explained by measuring DH. More research is needed to clarify and understand the properties required for the optimal IF protein composition for the prevention of CMA.

Effects of Lactobacillus rhamnosus LZ260E on allergic symptoms and intestinal flora in β-lactoglobulin-sensitized mice

Abstract

β-lactoglobulin (β-Lg) in milk is the main allergen that causes intestinal inflammation. Previous studies have reported that Lactobacillus rhamnosus LZ260E (LZ260E) has potential anti-allergic activity. However, the specific mechanism by which LZ260E exerts its anti-allergic activity is still unclear. This study investigated the effects of LZ260E on the β-Lg milk allergen mouse model. The results showed that oral administration of LZ260E reduced the spleen and thymus indexes of mice. In addition, oral administration of LZ260E reduced serum IgE, histamine, IL-4, and monocyte chemoattractant protein-1 (MCP-1) levels, upregulated the expression of IFN-γ, IL-10, TNF-α, and TGF-β, and repaired colon damage. The study also found that LZ260E regulated the changes in intestinal microbiota caused by allergies. In summary, LZ260E has anti-allergic effects by regulating intestinal flora and Th1/Th2 immune balance, and may be a functional probiotic for milk allergy.

Conclusion

This study explored the effects of LZ260E on the β-Lg-sensitized mouse model. LZ260E reduced the spleen and thymus indexes of mice, and reduced serum IgE, histamine, IL-4, and MCP-1 levels; in particular, it inhibited Th2 responses and relieved allergies by inducing Treg cells or Th1 cell differentiation. In addition, the experiment found that LZ260E repaired the damaged intestinal mucosa and regulated the structure of the intestinal microbiota. The results confirmed the hypothesis that LZ260E is a functional probiotic for milk allergy. The beneficial mechanism of LZ260E needs to be further studied, which will help the application of probiotics in the treatment of food allergies.

Potential allergenic peptides and key amino acids in glycated α-lactalbumin digestion products were studied by allergenicity evaluation and molecular dynamics simulation.

Abstract

This study aimed to identify potential allergenic peptides and key amino acids derived from glycated α-lactalbumin digestion products. Degranulation tests showed that amino acid sequences (AA) 37-50, AA80-90, AA94-104, and AA115-123 obtained from its digestion products were still allergenic, of which AA94-104 was identified as a potential allergenic peptide because it showed the highest release levels of β-hexosaminidase, interleukin-6, and histamine. Molecular docking showed that all four peptides could interact with MHC class II through hydrophobic interactions and hydrogen bonds. Molecular dynamics simulations confirmed that binding to AA94-104 resulted in a more compact MHC class II. Therefore, AA94-104 may be a potential allergenic peptide. Allergenicity analysis and molecular docking showed that leucine, isoleucine, asparagine, and tryptophan may be the key amino acids of AA94-104, as the lowest allergenicity was found in the corresponding mutant peptides. These results will provide theoretical guidance for the preparation of hypoallergenic bovine dairy products.

Conclusion

This study investigated the potential allergenic peptides and key amino acids in the digestion products of glycosylated ALA based on allergenicity evaluation and molecular dynamics simulation. Degranulation experiments showed that the synthetic peptides could still induce cell degranulation, among which AA94-104 had a stronger ability to promote the release of interleukin-6, β-hexosinase and histamine than the other three peptides. Molecular docking showed that all four peptides could interact with MHC class II through hydrophobic interactions and hydrogen bonds. The Rg/SASA value of the MHC class II-AA94-104 system decreased, confirming that binding with AA94-104 resulted in a more compact MHC class II structure. Therefore, AA94-104 may be a potential allergenic peptide from the digestion products of glycosylated ALA. The results showed that L96, I101, N102, and especially W104 were the key amino acids of AA94-104.

Ultrasound promotes temperature-dependent adsorption of β-lactoglobulin on starch nanoparticles for enhanced protein desensitization and alteration of physicochemical properties

Abstract

An effective method to reduce β-lactoglobulin (βLg) allergy by forming a protein corona on starch nanoparticles (SNPs) was presented, and the role of ultrasound in the temperature-dependent SNPs-βLg corona was systematically revealed through the βLg adsorption mechanism, and the changes in secondary structure and physicochemical properties were analyzed. It was found that adsorption was a spontaneous process and negatively correlated with temperature, while ultrasound treatment increased the theoretical maximum binding number of βLg from 4600 to 7800, accompanied by a higher binding affinity (Ka) of 58×106 M -1 and a greater change in the secondary structure of βLg containing (22±3.1)% of β-sheets. Functionally, ultrasound promoted the changes in the functional properties of βLg by adsorbing SNPs, inhibited the immunoglobulin E (IgE) binding capacity of βLg by (87±5)%, reduced the surface hydrophobicity and digestibility due to more reduction of β-folding, and increased the thermal stability and emulsification ability. The application potential of βLg and SNP in food can be promoted.

Conclusion

SNPs are considered as biosafe nanomaterials with high protein adsorption capacity, forming protein corona, causing changes in the structure and functional properties of adsorbed proteins. This adsorption provides a method for desensitization of allergenic proteins and has the potential to improve their functional properties. In this study, SNPs were used to adsorb βLg to form SNPs-βLg corona. The effects of ultrasound and temperature combination on the interaction between βLg and SNP were studied by combining the mechanism and determination of some physicochemical properties. The formation of SNPs-βLg corona is a spontaneous process and negatively correlated with temperature. Ultrasonic treatment showed a positive effect, increasing the number of adsorbed βLg molecules from 4600 to 7800 Ka and causing greater changes in the protein secondary structure. The structural changes induced by the protein corona inhibited the IgE binding ability of βLg, reduced its surface hydrophobicity and digestibility, and improved the thermal stability and emulsification ability of βLg. The use of ultrasound during the formation of SNPs-βLg particles enhanced these changes and provided opportunities for wider application of SNPs in the food industry.